This invention relates to a charging control apparatus for an image carrier and, more particularly, to an image forming apparatus, such as an electronic copying machine.
Generally, sensitivity (charging), of a photosensitive drum, serving as an image carrier for forming an electrostatic latent image in an electronic copying machine, is greatly influenced by change in ambient temperature or a temperature rise, in the copying machine caused by continuous copying operations. If copying operations are performed in the state wherein the sensitivity is changed, the quality of a copied image is thus degraded.
More specifically, charge retentivity (charging), of a photosensitive drum of amorphous selenium, amorphous silicon, or the like, is generally attenuated as the temperature of the drum rises. Therefore, a density distribution of the charge occurs, i.e., copying quality becomes nonuniform, resulting in poor quality of the copied image. Furthermore, if the drum exceeds a given temperature (or is below a given temperature), the photsensitive drum often malfunctions as an image carrier.
However, measures to alleviate such problems, caused by changes in temperature of the photosensitive drum, have never been taken.